Automatic control systems are critical to all sectors of industry such as process control, discrete control, batch control (process and discrete combined), machine tool control, motion control, and robotics. One of the strongest needs in modern control systems is development and use of “open” and “interoperable” systems. Open, interoperable systems allow control devices made by different manufacturers to communicate and work together in the same system without the need for custom programming. The movement toward open, interoperable control systems is driven by plant and enterprise management, application software suppliers, control device manufacturers, and end users. Plant and enterprise management want open, interoperable control systems because they need access to all of the control system information in order to provide the analysis needed to optimize the operation of the plant and enterprise. Client Application Software suppliers want open, interoperable control systems so that their software can access the control system data using standard computer platforms running standard operating systems, and interconnected by standard communication systems. Control device manufacturers want open, interoperable control systems because such systems allow them to sell their products to more end users while reducing development costs. End users want open, interoperable control systems so that they can select the best application software and control devices for their system regardless of the manufacturer.
In order for control systems to be truly open and interoperable, communications systems between devices, the user layer (above the communication system layers) in the devices, and the computer/application software integration architecture must be specified and made open. “Fieldbus” is the common term used to describe these types of automatic control systems.
One of the truly open and interoperable fieldbus control systems is the FOUNDATION™ fieldbus (“FF”) system provided by the Fieldbus Foundation (Austin, Tex.). The FF user layer and a lower speed 31.25 kilobits/second fieldbus (H1) is described in the above-mentioned '892 patent. A High Speed Ethernet (HSE) fieldbus, running at 100 megabit/second or higher speeds, is described in the above-mentioned '697 application. The '892 patent and the '697 application are assigned to the assignee of the present application.
H1 provides the open and interoperable solution for field level control capability and integration, and HSE provides the open and interoperable solution for distributed control on a very high performance communication system typically called a fieldbus control “backbone” network. The HSE control backbone aggregates information from lower speed control devices, e.g., the H1 devices and other control devices, which is used in supervisory and advanced control applications. The HSE control backbone aggregates data from high-speed control devices, e.g., HSE devices and other subsystems, and provides access/change of H1 and HSE control information by control system computers.
The plant/enterprise application software operates at the “client” and “server” levels in the control system hierarchy. An open and interoperable integrated fieldbus data server architecture (meaning client and server) is needed that will provide a framework and common specification for the “semantics” (how the application software understands the control system data) of fieldbus data, whether it is H1 or HSE data, or other control data. Prior to the present invention, client application software on the plant/enterprise computers had to be manually customize and adapt data received from each server that provided access to fieldbus or other control device data because each server identified and represented the same semantic information differently. A requirement for modem servers is to eliminate the need to manually customize or adapt client application software; the present application addresses this requirement.
Existing server specifications provide for automatic adaptation of very limited subsets of runtime data because this data can be understood through syntax only, e.g. message structure. For example, the OLE for Process Control (OPC) Specification from the OPC Foundation (Boca Raton, Fla.) provides for the limited adaptation through standardization of the basic access mechanism and syntax for runtime data, e.g. simple process variables (PV) and setpoints (SP). The OPC Specifications are general enough to allow extra information, called “properties” to define “class” attributes of the runtime data. Class attributes include “Device Description” (DD) information for the runtime data, e.g. help strings, engineering units, and parameter labels. Some DD information is complex, for example containing conditionals, menus, and methods (which are C programs). Additional class attributes are provided by “Capability Files” (CF) that describe the range of capability of the fieldbus device or other control device, e.g. maximum number of parameters, initial values of parameters, and maximum number of communication sessions. However, although OPC allow servers to define class attributes, there is no standardized definition for class attributes, thus limiting interoperability with, and automatic adaptation by, client application software
Further, even if class attributes could be standardized for server data, the client application software also needs to know which “instance” of the runtime data is being described by the class attributes. That is, the class attributes can tell the client application software what type of runtime data is being accessed, but they cannot identify the specific data that is being accessed. Instance information can be provided by accessing application directories (which locate the runtime data) in the fieldbus devices, but like class attributes, there is no standardized definition of the application directory information making interoperability and automatic adaptation of the client application software impossible.
Advanced Human/Machine Interface (“HMI”), trending, asset management, configuration, maintenance, diagnostic and plant/enterprise management application software must have access to runtime data and the class attributes and application directory semantic information that allows the software to automatically identify, interpret, and process the runtime data without manual intervention. Finally, to be efficient, the client application software must be able to access the runtime data and the semantic information through a single interface.
The OPC Specification is unable to automatically and efficiently support these advanced applications because there is no open and interoperable framework or specification for providing the above described semantic information to the client software applications through the same interface that is currently used to access runtime data.
What is needed is a framework and a common specification for an integrated fieldbus data server architecture that can provide semantics of runtime data, both simple and complex, to the client application software.
What is needed is a framework and a common specification for an integrated fieldbus data server architecture that migrates support for existing plant/enterprise client application software, e.g., HMI and other OPC software applications, while standardizing and integrating the semantics needed for automatic identification, interpretation, and processing of runtime data by advanced client application software, e.g., plant/enterprise management, configuration, maintenance, and diagnostics application software.
What is needed is an integrated fieldbus data server architecture that complements H1, HSE and other fieldbus architectures so the plant/enterprise application software can automatically interpret the runtime data using corresponding semantic information.
What is needed is an integrated fieldbus data server architecture provides a single interface for access of the runtime data and corresponding semantic information by the plant/enterprise application software.